Glossary · Heating, cooling & ventilation
HSPF / HSPF2
Also called: heating seasonal performance factor
A heat pump's heating efficiency averaged over a whole heating season; higher is better, and HSPF2 numbers can't be compared directly with older HSPF.
What it means
HSPF2 replaced HSPF in 2023 when US test procedures changed, and DOE says the old and new numbers aren't directly comparable. Ratings also depend on the climate assumed: Region IV represents a US Midwest-type climate, while Region V is colder, closer to Ottawa. Dividing HSPF by 3.412 gives an approximate seasonal COP.
Why it matters in an audit
It's the main heating-efficiency number on heat pump spec sheets, rebate rules and AHRI certificates.
Typical numbers
Reference values with their sources. Your auditor’s report gives the figure for your own house.
| What | Value | Source |
|---|---|---|
| US federal minimum (since Jan 1, 2023) | Split heat pumps HSPF2 7.5; single-package 6.7 | www1.eere.energy.gov ↗ |
| ENERGY STAR (spec 6.2) | Split ≥ 7.8; single-package ≥ 7.2; Cold Climate ≥ 8.5 ductless or ≥ 8.1 ducted | energystar.gov ↗ |
| NEEP cold-climate spec v4.0 | Above 7.7 ducted; above 8.5 ductless | neep.org ↗ |
In the United States
US product literature and the AHRI directory usually show HSPF2 for Region IV.